Influence de plusieurs variables environnementales sur les extrêmes variations d’abondance de Lestes macrostigma au sein du réseau de mares temporaires méditerranéennes de la réserve naturelle des Tre Padule de Suartone en Corse

Abstract

Lestes macrostigma is a damselfly whose populations exhibit marked interannual abundance variations. A better understanding of this phenomenon represents a stake for the management of this taxon frequently threatened in Europe. The work that was carried out therefore focused on analyzing the links between the annual abundance of L. macrostigma and several environmental parameters in order to study the origin of these fluctuations. In this context, monitoring was carried out on the network of Mediterranean temporary ponds of Tre Padule de Suartone in Corsica for seven years. The correlations calculated with the sixteen environmental variables studied show that the greater the water levels and precipitation accumulations in the ponds during and near the period of L. macrostigma emergence, the greater the annual abundance of individuals measured. The correlation analysis shows the very important and direct link between the abundance of L. macrostigma and the water levels of the ponds during the period of emergence of the species. This parameter seems to have a decisive impact on the area of aquatic micro-habitats favorable to larval development. The results obtained also allowed to demonstrate that the increase in maximum water temperatures during the period of emergence of this damselfly is negatively correlated with the abundance. This phenomenon thus suggests the existence of lethal threshold, which remains to be confirmed by further studies. The air temperatures as well as the minimum and average water temperatures during the period of emergence of the species seem on the other hand to have only a very weak impact on the abundance of L. macrostigma on the site studied.